JP7299422B2 - Planar lighting device - Google Patents

Description

The present invention relates to a planar illumination device.

2. Description of the Related Art Planar illumination devices used as backlights of liquid crystal display devices are known (see, for example, Patent Documents 1 to 3). Such a planar illumination device includes an edge light type in which light is incident from one side surface (light incident side surface) of the light guide plate and light is emitted from one main surface of the light guide plate, and an edge light type in which light is emitted from one main surface of the light guide plate. There is a direct type in which a plurality of light sources are arranged at the bottom.

Any type of planar lighting device is often provided with a bottom frame in which components are housed and a top frame that closes the opening side of the bottom frame. The top frame also serves to shield the periphery of the effective light emitting area from light and prevent components housed inside from protruding. In general, the bottom frame is formed by metal die casting or the like, and the top frame is often formed by sheet metal or by resin molding.

On the other hand, in recent years, in addition to flat types, curved types of liquid crystal display devices for automotive applications have increased, and along with this, not only flat types but also curved types of planar lighting devices have increased. . Therefore, it is becoming important for the structure of the planar lighting device to be able to cope with both flatness and curvature. In addition, there has been a strong need for a narrower frame than before.

JP 2021-12884 A Japanese Unexamined Patent Application Publication No. 2015-18700 JP 2018-37416 A

As described above, the top frame is often formed by sheet metal or resin molding, but sheet metal and resin molding have advantages and disadvantages. That is, in the case of sheet metal, it is possible to make the frame as thin as a few millimeters, so it is advantageous for narrowing the frame. Not compatible with frames. On the other hand, in the case of resin molding, it is easy to form a curved top frame, but there is a limit that the molding thickness cannot be made smaller than about 1 mm, so it is difficult to narrow the frame.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a planar lighting device that can easily adapt to both flatness and curvature and that is advantageous for narrowing the frame.

To solve the above-described problems and achieve an object, a planar lighting device according to one aspect of the present invention includes a bottom frame and a top cover. Said bottom frame is made of die-cast and has an end face facing the output side and forming an opening with an inner edge . The top cover has a frame-like shape, and includes an intermediate layer in which the outer periphery of the incident-side surface is arranged on the end surface , and a light-shielding layer fixed to substantially the entire output-side surface of the intermediate layer. , is flexible . The top cover has a plurality of strip-shaped members, and at one corner of the top cover, the long side of the intermediate layer of the first member is attached to the short side of the intermediate layer of the second member. are opposed to each other, the light shielding layer of the second member is arranged to cover the facing portion of the intermediate layers, and the light shielding layer of the first member is disposed on the long side of the light shielding layer of the second member. The short sides face each other, and the intermediate layer of the first member is arranged to cover the opposing portions of the light shielding layers.

The planar lighting device according to one embodiment of the present invention can easily adapt to both flatness and curvature, and can be advantageous for narrowing the frame.

FIG. 1 is a plan view showing an example of the appearance from the exit surface side of a planar illumination device according to one embodiment. FIG. 2 is a front view showing an example of a flat type planar illumination device. FIG. 3 is a front view (1) showing an example of a curved type planar illumination device. FIG. 4 is a front view (2) showing an example of a curved type planar illumination device. FIG. 5 is a YY cross-sectional view showing an example of the flat type planar illumination device of FIGS. 1 and 2. FIG. FIG. 6A is an enlarged view of portion A of FIG. FIG. 6B is an enlarged view of portion B of FIG. FIG. 7 is a diagram (1) showing an example of the structure of the intermediate layer and the light shielding layer at the corner of the top cover. FIG. 8 is a diagram (2) showing an example of the structure of the intermediate layer and the light shielding layer at the corner of the top cover.

A planar illumination device according to an embodiment will be described below with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, the dimensional relationship of each element in the drawings, the ratio of each element, and the like may differ from reality. Even between the drawings, there are cases where portions with different dimensional relationships and ratios are included. In addition, the contents described in one embodiment and modification are in principle similarly applied to other embodiments and modifications.

FIG. 1 is a plan view showing an example of the appearance of a planar illumination device 1 according to one embodiment, viewed from the exit surface side. In FIG. 1, for convenience of explanation, the direction along the long side of the housing of the planar lighting device 1 is the X-axis direction, the direction along the short side of the housing is the Y-axis direction, and the direction along the thickness of the housing is shown. is the Z-axis direction, but the orientation of the planar illumination device 1 during use is arbitrary.

In FIG. 1, the planar illumination device 1 has a substantially rectangular and substantially flat plate-like outer shape, and a housing is configured by covering the opening side of the bottom frame 2 with a top cover 14 . The shape of the top cover 14 is not limited to rectangular, but may be circular, elliptical, or polygonal. .

FIG. 2 is a front view showing an example of a flat-type planar illumination device 1, and side walls of the bottom frame 2 extend linearly in the X-axis direction. FIG. 3 is a front view showing an example of the curved type planar lighting device 1, and the side wall of the bottom frame 2 is curved so as to be concave toward the output surface side (upper side in the drawing). FIG. 4 is a front view showing another example of the curved type planar illumination device 1, and the side wall of the bottom frame 2 is curved so as to be convex toward the output surface side (upper side in the figure).

FIG. 5 is a YY sectional view showing an example of the flat-type planar illumination device 1 of FIGS. 1 and 2. As shown in FIG. The curved type planar illumination device 1 is curved in the X-axis direction, but has the same internal configuration. Here, an edge light type is used as an example, but a direct type in which light sources arranged vertically and horizontally in a plane are accommodated may be used.

In FIG. 5, the bottom frame 2 is made of die-casting, and has a substantially box-like shape with a bottom and no lid. An opening is formed by a bottom surface 2a and side wall inner surfaces 2b rising from the periphery of the bottom surface 2a. A stepped portion 2d is provided inside the end surface 2c of the opening.

A part of the light guide plate 7 and the reflector 4 are adhesively fixed to the light incident side (left side in the drawing) of the bottom surface 2a of the bottom frame 2 via a fixing member 3 such as double-sided tape. The light guide plate 7 has a substantially rectangular and substantially flat plate-like outer shape and is made of a transparent resin such as polycarbonate. emit light from the main surface of The reflector 4 is a sheet-like member of white or the like having high diffuse reflection characteristics, and reflects light leaking from the back surface of the light guide plate 7 and returns the light to the light guide plate 7 to improve light efficiency. A strip-shaped reflector 6 is also adhesively fixed to the inner surface of the side wall on the end side of the light guide plate 7 via a fixing member 5 such as a double-sided tape.

A substantially strip-shaped substrate 12 made of FPC (Flexible Printed Circuits) or the like is adhesively fixed to the side wall inner surface 2b on the light incident side with a fixing member 11 such as double-sided tape. A plurality of light sources 13 such as LEDs (Light Emitting Diodes) are arranged in a line on the substrate 12 so as to emit light toward the light incident side surface 7 a of the light guide plate 7 . The illustrated light source 13 is of a top-view type that emits light from the top surface, and emits light with the normal direction (X-axis direction) of the substrate 12 as a substantially central axis. By changing the arrangement of the substrate 12, a side-view type light source that emits light from the side can also be used.

Optical sheets 8 to 10 are placed on the exit surface side of the light guide plate 7 . The optical sheet 8 is, for example, a diffuser (diffusion film). The optical sheet 9 is, for example, a prism sheet such as BEF (brightness enhancement film manufactured by 3M). The optical sheet 10 is, for example, a prism sheet such as DBEF (brightness enhancement film manufactured by 3M).

A top cover 14 is adhesively fixed to the output side of the bottom frame 2 . FIG. 6A is an enlarged view of portion A of FIG. FIG. 6B is an enlarged view of portion B of FIG.

In FIGS. 5, 6A and 6B, the top cover 14 is frame-shaped (substantially square-shaped when viewed from above) and is composed of an intermediate layer 15 , a diffuse reflection layer 16 and a light shielding layer 17 . The intermediate layer 15 is a double-faced tape with a PET material as a base material, and the outer peripheral portion of the incident side (lower side in the drawing) is adhesively fixed to the stepped portion 2 d of the bottom frame 2 . The diffuse reflection layer 16 is, for example, a PET material colored white or gray, and extends from predetermined positions P1 and P3 inside the stepped portion 2d on the incident side surface of the intermediate layer 15 to positions P2 and P4 on the inner edge. It is glued and fixed. The light shielding layer 17 is, for example, a PET material colored black, and is adhesively fixed to substantially the entire surface of the intermediate layer 15 on the output side. The material of the top cover 14 may be SUS (stainless steel) instead of the PET material. In that case, it has better thermal stability and better results in reliability tests. When using SUS for the top cover 14, there is a problem of high cost, but this can be solved by adopting the structure (strip structure) shown in FIGS. 7 and 8, which will be described later. In addition, the diffuse reflection layer 16 has a brightness and brightness of a region near the inner end positions P2 and P4 in the effective light emitting region (the region between the inner end positions P2 and P4 not covered with the top cover 14). Although it is effective in improving uniformity, it may not necessarily be provided depending on the required specifications for luminance.

In this way, by forming the housing of the planar lighting device 1 from the bottom frame 2 and the top cover 14, it is possible to easily adapt to both flatness and curvature, which is advantageous for narrowing the frame. can do. That is, since the top cover 14 is flexible, it can easily adapt to the curvature of both flatness and curvature. The frame can be narrowed by the amount of clearance. In addition, unlike the conventional top frame, the top cover 14 does not require a process of fitting to the bottom frame, and can be assembled in the same process as tape application, facilitating assembly and automating assembly.

In addition, since the intermediate layer 15, the diffuse reflection layer 16 and the light shielding layer 17 are made of PET material, the linear expansion due to the temperature change can be reduced, and the deformation and peeling of the top cover 14 can be prevented. By coloring the light shielding layer 17 black, the light shielding property can be improved. By coloring the intermediate layer 15 white, black, or gray, the brightness around the opening of the top cover 14 can be adjusted. A cover glass of a liquid crystal panel (not shown) is adhered and fixed to the end surface 2c of the bottom frame 2, so that connection with the liquid crystal panel can be easily performed and integrated as an LCD (Liquid Crystal Display) module. .

The above-described top cover 14 is, for example, made by cutting out rectangular sheets from the inside of three rectangular sheets to form a frame shape. , the material yield is poor, making it difficult to reduce costs. The configuration of the top cover 14 capable of increasing the yield of materials will be described below.

7 and 8 are diagrams showing examples of structures of the intermediate layer and the light shielding layer at the corners of the top cover 14. FIG. 7 shows the state of the intermediate layer 15 and the light shielding layer 17 in the corner portion C before bonding, and FIG. 8 shows the state of the intermediate layer 15 and the light shielding layer 17 in the portion C after bonding.

7 and 8, the top cover 14 is formed from a plurality of strip-shaped members. When the top cover 14 is frame-shaped and rectangular, it is effective to use four members corresponding to four sides. Although the diffuse reflection layer 16 is omitted in FIGS. 7 and 8, the diffuse reflection layer 16 is also provided.

At one corner portion C of the top cover 14, the short side of the intermediate layer 15-2 of the second member is in contact with the long side of the intermediate layer 15-1 of the first member extending in the lateral direction of the figure (or facing and adjacent to each other), the light shielding layer 17-2 of the second member is arranged to cover the contact portion (opposing portion) between the intermediate layers 15-1 and 15-2. On the other hand, the short side of the light shielding layer 17-1 of the first member contacts (or faces and adjoins) the long side of the light shielding layer 17-2 of the second member extending obliquely in the figure, and the first member The intermediate layer 15-1 is arranged to cover the contact portion (opposing portion) between the light shielding layers 17-1 and 17-2 from the lower side. In other words, the contact portion (facing portion) between the intermediate layers 15-1 and 15-2 and the contact portion (facing portion) between the light shielding layers 17-1 and 17-2 are positioned so as not to overlap each other (this embodiment morphology are arranged at right angles to each other). Since the intermediate layer 15-1 closes the gap between the contact portions (opposing portions) of the light shielding layers 17-1 and 17-2, the intermediate layer 15-1 is required to have a light shielding property. -1 (as well as the intermediate layer 15-2) is preferably a double-sided tape whose base material is a PET material colored black, for example.

7 and 8, the diffusion reflection layer 16 is not shown, but like the intermediate layer 15 and the light shielding layer 17, the diffusion reflection layer 16 is also formed in a strip-like shape, and has one side at the corner. They are arranged so that the other short side touches or faces the long side and is adjacent to the other. In this case, the diffuse reflection layer of the second member may be arranged so as to cover the contact portion (opposing portion) between the intermediate layers 15-1 and 15-2. They may be arranged so as to contact or face the diffuse reflection layer of the first member at their contact portions (facing portions).

In this way, the top cover 14 is formed from a plurality of strip-shaped members, so that the base material can be saved and the cost can be reduced as compared with the case where the inside of the sheet is punched out and the punched inner part is discarded. be able to. Further, in the case of the rectangular top cover 14, the plurality of members are four members corresponding to the four sides, and the frame-shaped top cover 14 can be configured with the minimum number of members. In addition, by covering the contact portion between the intermediate layers with the light shielding layer, it is possible to prevent light from leaking from the connection portion between the members and to strengthen the connection between the members.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention.

As described above, the planar illumination device according to the embodiment includes a die-cast bottom frame having a stepped portion inside the end face of the opening, and an intermediate layer whose outer periphery of the entrance-side surface is fixed to the stepped portion. , and a light-shielding layer fixed to substantially the entire surface of the output side of the intermediate layer. As a result, both flatness and curvature can be easily accommodated, which is advantageous for narrowing the frame.

That is, since the top cover is flexible, it can easily adapt to the curvature of both flat and curved surfaces, and since there is no side wall like the top frame, clearance between the side wall and the side wall of the bottom frame is small. It is possible to narrow the frame by the amount. In addition, unlike the conventional top frame, the top cover does not require the process of fitting it to the bottom frame, and can be assembled in the same process as tape application, making assembly easy and automated.

Further, the diffuse reflection layer is fixed from the inner side of the stepped portion to the inner end portion of the incident side surface of the intermediate layer. As a result, it is possible to improve luminance uniformity by improving the luminance of the effective light emitting area in the vicinity of the ineffective light emitting area covered with the top cover.

The intermediate layer is a double-faced tape made of PET material, and the diffuse reflection layer and the light shielding layer are made of PET material. As a result, linear expansion due to temperature change can be reduced, and deformation and peeling of the top cover can be prevented.

Also, the light shielding layer is colored black. Thereby, the light shielding property can be improved.

Also, the diffuse reflection layer is colored white, black or gray. Thereby, the brightness around the opening of the top cover can be adjusted.

Also, the top cover is formed from a single member or a plurality of strip-shaped members. This makes it possible to select the method of manufacturing the top cover. When formed from a plurality of members, compared with the case where the inside of the sheet is punched out and the punched inner portion is discarded, the base material can be saved and the cost can be reduced.

The plurality of members are four members corresponding to the four sides of the frame-shaped rectangular top cover. As a result, the frame-shaped top cover can be configured with a minimum number of members.

Further, at one corner of the top cover, the long side of the intermediate layer of the first member faces the short side of the intermediate layer of the second member, and the light shielding layer of the second member is the portion where the intermediate layers face each other. is placed over the As a result, when the top cover is constructed from a plurality of strip-shaped members, it is possible to prevent light from leaking from the connecting portions of the members and to strengthen the connection between the members.

Also, the cover glass of the liquid crystal panel is adhesively fixed to the end face of the opening of the bottom frame. This facilitates the connection with the liquid crystal panel and enables integration as an LCD module.

In addition, the bottom frame accommodates the light source and the light guide plate, which are components of the edge light type, or the light sources arranged vertically and horizontally in a plane, which is the component of the direct type. This makes it possible to deal with different types of device configurations.

Moreover, the present invention is not limited by the above embodiments. The present invention also includes those configured by appropriately combining the respective constituent elements described above. Further effects and modifications can be easily derived by those skilled in the art. Therefore, broader aspects of the present invention are not limited to the above-described embodiments, and various modifications are possible.

Reference Signs List 1 planar illumination device 2 bottom frame 2a bottom surface 2b side wall inner surface 2c end surface 2d step portion 3 fixing member 4 reflector 5 fixing member 6 reflector 7 light guide plate 7a light incident side surface 8, 9 , 10 optical sheet, 11 fixing member, 12 substrate, 13 light source, 14 top cover, 15 intermediate layer, 16 diffuse reflection layer, 17 light shielding layer

Claims (10)

a die-cast bottom frame having an end face facing the output side and forming an opening with an inner edge;
A flexible frame-shaped top having an intermediate layer having an incident-side surface whose outer periphery is disposed on the end surface, and a light-shielding layer fixed to substantially the entire surface of the output-side surface of the intermediate layer. a cover;
with
The top cover has a plurality of strip-shaped members,
At one corner of the top cover,
The long side of the intermediate layer of the first member faces the short side of the intermediate layer of the second member, and the light shielding layer of the second member covers the opposing portions of the intermediate layers. is,
The long side of the light shielding layer of the second member faces the short side of the light shielding layer of the first member, and the intermediate layer of the first member covers the opposing portions of the light shielding layers. to be
Planar lighting device. a die-cast bottom frame having an end face facing the output side and forming an opening with an inner edge;
A flexible frame-shaped top having an intermediate layer having an incident-side surface whose outer periphery is disposed on the end surface, and a light-shielding layer fixed to substantially the entire surface of the output-side surface of the intermediate layer. a cover;
with
A diffuse reflection layer fixed from the end face side to the inner end of the incident side surface of the intermediate layer,
The diffuse reflection layer is sheet-like,
A light guide plate and one or more optical sheets are arranged between the inner bottom surface of the bottom frame and the top cover, and the one or more optical sheets are arranged closest to the emission surface side of the planar illumination device. A gap is formed between the optical sheet and the top cover over the entire area facing each other so that the optical sheet does not come into contact with the top cover.
Planar lighting device. a die-cast bottom frame having an end face facing the output side and forming an opening with an inner edge;
A flexible frame-shaped top having an intermediate layer having an incident-side surface whose outer periphery is disposed on the end surface, and a light-shielding layer fixed to substantially the entire surface of the output-side surface of the intermediate layer. a cover;
with
The light shielding layer is made of a stainless steel material,
The light shielding layer is sheet-shaped,
A light guide plate and one or more optical sheets are arranged between the inner bottom surface of the bottom frame and the top cover, and the one or more optical sheets are arranged closest to the emission surface side of the planar illumination device. A gap is formed between the optical sheet and the top cover over the entire area facing each other so that the optical sheet does not come into contact with the top cover.
Planar lighting device. The intermediate layer is a double-sided tape having a PET material as a base material,
The diffuse reflection layer and the light shielding layer are PET materials,
3. The planar illumination device according to claim 2. The light shielding layer is colored black,
The planar lighting device according to any one of claims 1 to 4. The diffuse reflection layer is colored white or gray,
The planar illumination device according to claim 2 or 4. The top cover is formed from a single member or a plurality of strip-shaped members,
4. The planar lighting device according to claim 2 or 3. The plurality of members are four members corresponding to four sides of the frame-shaped rectangular top cover,
The planar illumination device according to claim 1 or 7. A cover glass of a liquid crystal panel is adhesively fixed to the end surface of the bottom frame.
The planar lighting device according to any one of claims 1 to 8. The bottom frame accommodates a light source and a light guide plate, which are components of an edge-light type, or a light source arranged vertically and horizontally in a plane, which is a component of a direct type.
The planar lighting device according to any one of claims 1 to 9.

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